


Exercise of Trust

by Mercy_Run



Category: Undertale (Video Game)
Genre: Aftercare, BDSM, Collars, Dirty Talk, Domination/submission, Ectobiology, M/M, Non-verbal Safe-word, Selfcest, Smut, Tentacles, breath play
Language: English
Status: Completed
Published: 2018-04-09
Updated: 2018-04-09
Packaged: 2019-04-20 16:32:46
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,206
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14265117
Author URL: https://archiveofourown.org/users/Mercy_Run/pseuds/Mercy_Run
Summary: Sans wants to indulge in Red’s more wild fantasies and finds that submission fits him just as well as the collar his lover gave him.





	Exercise of Trust

**Author's Note:**

> Third Place prize for the Nethertale Concept Contest for ashethedevil/homestucksfaygo ! I hope this is similar to what you had in mind for these two! Thank you so much for your hard work!

Sans shifted wordlessly into his alternate’s caress, his blown eye-lights searching Red’s expression. His lover appeared unusually solemn for both skeleton monsters to be so far into arousal but the smaller skeleton wasn’t surprised. Their play together was markedly less risky than what Sans had agreed to today. He had expected for Red to be lost to his own passion and excitement, but the other monster appeared to be one hundred percent in control. It was arousing and reassuring that his Dom kept such a collected head even in the heat of the moment.

“yer doing okay, sweetheart?” Red rumbled, intense expression trained on his face.

He silently nodded, mindful that he had been asked to not speak during this scene. If things got too intense and he needed to use his safe-word, Sans and Red had worked on a signal to let the other know without speaking. ‘Tapping out’ so to speak. The other’s sharp fangs pulled upwards in satisfaction, a soft noise of metal on metal as the smaller skeleton was pulled up by the chain attached to his collar. Shifting restlessly at the expression on his Dominant’s skull, the small skeleton moaned as Red ground their naked pelvis’ together.

His arms twitched longingly at his sides, but Sans didn’t follow the impulse to embrace Red. The other monster saw the movement and chuckled deeply in amusement, the sound sending a jolt of lust down his spine.

“yer know i told yer not to touch me, lil’ one. yer gonna be good for me?”

Sans shivered at the undertone of authority and nodded from his position, Red softening a bit before tugging his smaller lover closer by his collar. His Dom immediately devoured his mouth, the slide of the other skeleton’s tongue against his own causing him to moan into the kiss. The sound was swallowed greedily by Red before he was released, gasping for air. Shoving his smaller body into the sheets of their shared bed, the larger skeleton purred in his rib-cage as Sans choked; his pelvis filling with cyan magic before it formed into a short blue cock and entrance.

“heh heh… looks like yer ready to go to me,” Red’s fingers ghosted over his shaft, causing it to twitch before sinking a single phalange into his tight passage, “fuck, yer always so responsive for me, sweetheart. spread yer legs a little more, let me see yer…”

The smaller skeleton flushed with light blue magic before obeying, sockets lidding as Red teased him open. A whine slipped from between his teeth, knees relaxing as far apart as they could go, glancing down his body to watch his Dominant’s fingers through the transparent magic. Sans’ face colored a bit more at the squelching wet noises his body was making as his arousal got stronger, a bead of pre gathering on the head of his cock.

Red’s other hand came up and smeared the liquid into the tip slowly as Sans’ body jerked in response, chain rattling as his voice broke on a moan.

“yer ready for the main event, lil’ one?”

At the larger skeleton’s purred words, Sans nodded frantically. His pelvis twitched up searchingly when Red’s fingers withdrew, causing his Dom to rumble in pleasure. His body was easily maneuvered to Red’s; the blunt tip of the other’s cock butting against his loosened entrance before slowly sinking inside.

“hah…ah~!”

“fuck…” Red hissed as the base of his magic became flush with Sans’ own, both skeletons taking a moment to adjust. It didn’t matter how many times they did this. There would always be that overwhelming connection in them both when they were joined like this. A beat passed in stillness before a shimmer of crimson magic signaled Red summoning tentacles, a smirk pulling at his sharp smile as Sans’ shuddered.

One immediately snatched up his wrists and pinned them down above his skull. Probably for the best because Sans had been itching with the need to touch his Dominant… Another one deftly coiled around his blue cock and squeezed. Sans’ eye-lights blew wide, hips bucking and earning him a brutal thrust from his lover. Red gripped his hips and held him down, expression easing into something dark and protective, screaming opposing signals to the smaller skeleton’s mind.

The remaining tentacle hovered over Sans’ neck meaningfully.

“remember yer signal, sweetheart..?”

Sans nodded, able to gather his thoughts enough that he kept it in the back of his mind. Red grinned, pleased.

“good boy…” He purred, the tentacle wrapping loosely around his vulnerable neck just below his collar, “now sing for me, sans…”

The smaller skeleton wasn’t given any further warning before his Dom’s hips snapped back and then slammed home, causing his voice to cry out in shock. Red didn’t alter his pace at all, rutting against him like a mindless animal in heat. The snarl rumbling constantly in Red traveled down the coiled tentacles, the one at his cock contracting in the off-beats between the other monster’s thrusting.

“ahhhh~!” Sans’ instinctively fought against the magical tendrils, teeth parting to reveal his fangs. His tongue lolled and drool slicked down his chin as Red took his body roughly, jostling him as he didn’t get a reprieve from the pleasure. Red’s growling reached a new pitch as Sans’ magic contracted around his shaft.

“fuck, yeah… squeeze my cock just like that… yer so hot and tight and mine!”

Sans whined, convulsing around Red and thrusting listlessly into the tentacle pushing him closer to release.

“yer gonna cum?” The larger skeleton laughed, “already? …so needy. alright. never say yer master isn’t giving…”

The tentacle around his neck slowly tightened and Sans’ desperate cries were choked off into barely there whimpers. His head felt lighter as his invisible ecto-biology was affected, soul pulsing slower as he couldn’t intake a breath of air. His vision dimmed and his large white eye-lights fractured, hips mindlessly meeting Red’s brutal pace.

His world narrowed down on the expression on Red’s face, the lack of air and his magic giving way to his Dom’s single-minded fucking, pressing his insides open to accommodate his dick. The moment drew out and Sans’ fingers twitched, nearly pinching the tentacles in their signal before-

His body bowed and convulsed underneath Red, his magic clamping down so hard around his lover that it brought out a sob from the other monster. His cock jerked in the stroking tendril before spurt after spurt shot out of the tip. Sans came so hard that his blue magic hit Red’s face as his Dom swore and praised him, riding his own orgasm as he milked his own large shaft on the smaller skeleton’s walls.

The world nearly faded before the tentacle released him, a desperate gasp for air bringing his consciousness back. He barely registered Red pulling out of him and leaving him for a short time. The monster could only breathe slow and bask in the afterglow…

It was only when his body was wrapped up into a cocoon of warmth and feeling his soul sync with Red’s that Sans managed to pull out of his daze. Large ruby eye-lights stared down at him, a gentle expression on his Dom’s face as he was embraced tight.


End file.
